Posology : מינונים

4.2      Posology and Method of Administration
Method of administration: Foscarnet should be administered by the intravenous route only, either by a central venous line or in a peripheral vein.
When peripheral veins are used, the solution of foscarnet 24mg/ml must be diluted.
Individually dispensed doses of foscarnet should be aseptically transferred and diluted with equal parts of 0.9% sodium chloride (9mg/ml) or 5% dextrose (50mg/ml) by the hospital pharmacy. The diluted solutions should be used as soon as possible after preparation but can be stored for up to 24 hours if kept refrigerated.


The solution of foscarnet 24mg/ml may be given without dilution via a central vein.
Adults: Induction therapy for CMV retinitis: Foscavir 24mg/ml is administered over 2- 3 weeks depending on the clinical response, as intermittent infusions every 8 hours at a dose of 60mg/kg in patients with normal renal function. Dosage must be individualised for patient’s renal function (see dosing chart below). The infusion time should not be shorter than 1 hour.


Maintenance therapy: For maintenance therapy, following induction therapy of CMV retinitis, Foscavir 24mg/ml is administered seven days a week as long as therapy is considered appropriate. In patients with normal renal function it is recommended to initiate therapy at 60 mg/kg. Increase to a dose of 90-120 mg/kg may then be considered in patients tolerating the initial dose level and/or those with progressive retinitis. A number of patients have received 90 mg/kg over a 2 hour period as a starting dose for maintenance therapy. Dosage must be reduced in patients with renal insufficiency (see dosage chart at end of dosage section).


Patients who experience progression of retinitis while receiving maintenance therapy may be re-treated with the induction regimen.
Caution: Do not administer Foscavir 24mg/ml by rapid intravenous injection.
Table 1 - Foscavir 24mg/ml Dosing Chart
Induction Therapy
Creatinine                          CMV
Clearance
Every 8 Hours
(ml/kg/min)
(mg/kg)
>1.6                        60
1.6-1.4                        55
1.4-1.2                        49
1.2-1.0                        42
1.0-0.8                        35
0.8-0.6                        28
0.6-0.4                        21
<0.4                        Treatment not recommended
CMV Maintenance Therapy


Creatinine                         One Infusion
Clearance                          Dose:
(ml/kg/min)                        (mg/kg/day in not less than one hour)
>1.6                   60*
1.6-1.4                   55
1.4-1.2                   49
1.2-1.0                   42
1.0-0.8                   35
0.8-0.6                   28
0.6-0.4                   21
<0.4                   Treatment not recommended

*A number of patients have received 90 mg/kg as a starting dose for maintenance therapy.


Foscavir 24mg/ml is not recommended in patients undergoing haemodialysis since dosage guidelines have not been established.


Hydration: Renal toxicity of Foscavir 24mg/ml can be reduced by adequate hydration of the patient. It is recommended to establish diuresis by hydration with 0.5-1.0 Litre of normal saline at each infusion. In compliant patients, oral hydration with similar hydration regimens has been used. Clinically dehydrated patients should have their condition corrected before initiating Foscavir 24mg/ml therapy.


Elderly: As for adults.

Paediatric population: The safety and efficacy of foscarnet in children have not been established. (Please refer to Sections 4.4 Special Warnings and Special Precautions for Use and 5.3 Preclinical safety data.)


Renal or hepatic insufficiency: The dose must be reduced in patients with renal insufficiency, according to the creatinine clearance level as described in the table above. Dose adjustment is not required in patients with hepatic insufficiency.